Spring doesn’t officially arrive until March 20, but you wouldn’t think so in Hampton Roads and the rest of the state. Trees are budding, birds are chirping and, believe or not, insects are hatching during what’s been one of the mildest winters in recent memory.

According to the National Weather Service, the average January temperature in Hampton Roads was 47.2 degrees, almost 7 degrees above normal. December was similar — the thermometer was 6.2 degrees above average.

The trend, which began in November, rings true in Maryland and North Carolina. So, what gives?

“The colder air has been locked up north,” said Tim Gingrich, a meteorologist at the weather service’s Wakefield office.

Gingrich said the U.S. is locked in a La Nina, a weather pattern characterized by cool sea surface temperatures in the Pacific Ocean. As it spreads across the nation, La Nina blocks the northern jet stream — a fast-flowing, narrow air current — from reaching points south.

While not common, the persistent warm weather is within Virginia’s historical range, Gingrich said. Nevertheless, it’s confusing the region’s flora.

Plants respond to temperature changes and many are acting like its March or April, he said. The phenomena could mean trouble for fruit trees, such as apples and pears. If their buds bloom early, they could be damaged by a sudden cold snap.

The weather has accelerated the arrival of various insects, Weiss said — don’t worry, no mosquitoes yet.

Parts of the Chesapeake Bay, especially shallow areas in the north, were covered in ice last year. The bay’s temperature Wednesday hovered in the low 40s, an indication it may warm up quicker this spring and summer.

That could lead to an early influx of jellyfish, said Deborah Steinberg, professor at the Virginia Institute of Marine Science in Gloucester Point.

A warm weather benefit: it’s costing less to heat homes. Richmond-based Dominion Resources, the state’s dominant utility company, reported last week that revenue was down 15 percent from last quarter, a dip due partly to weather in November and December.

Temperatures are expected to return to normal this weekend, with highs near 50 degrees, before again inching upward on Monday. There is some indication that February will stay closer to normal, Gingrich said, but it’s too early to say so definitively.

Which is fine with Shoe, who moved to Newport News from North Carolina about two years ago to be closer with family.